If you're looking to entertain your young kids, definitely MK. If they remember your last trip, they won't enjoy EP at all. If they don't remember your last trip and you really want to do EP, then do it. If they don't know any better, then they'll love EP. There is plenty to do there with them (kidcot in WS, Nemo, Innoventions, Meet & Greets) but it won't compare to MK if they remember going there.